Among the assets present in the Gigaleak, a large-scale leak of internal server data from Nintendo in 2020, are sprites for what appears to be an early version of Hookbill the Koopa with a radically different design. This iteration bears a strong resemblance to Birdo, though with numerous Koopa-like elements (including the shell, body type, and gait) that would be retained in the final game. This early design appears to explain why Hookbill the Koopa regurgitates eggs when Yoshi stomps on his head, given that spitting eggs is one of Birdo's staple abilities in the Mario series. Furthering this, some of the early sprites include ones for spitting spiked balls as an attack.